优先级队列是在普通FIFO队列的基础上，增加了优先级的权重，优先级高的元素，将优先出队列，从而得到优先处理。

代码示例如下：

import heapq

class PriorityQueue:
    def __init__(self):
        self._queue = []
        self._index = 0
        
    def push(self, item, priority):
        heapq.heappush(self._queue, (-priority, self._index, item))
        self._index += 1
        
    def pop(self):
        return heapq.heappop(self._queue)[-1]

class Item:
    def __init__(self, name):
        self.name = name
    def __repr__(self):
        return 'Item({!r})'.format(self.name)
    
pq = PriorityQueue()
pq.push(Item('laomeng'), 1)
pq.push(Item('laozhang'), 10)
pq.push(Item('laoli'), 3)
pq.push(Item('laoliu'), 5)

print(pq.pop())
print(pq.pop())
print(pq.pop())
print(pq.pop())

参考资料：

http://docs.python.org/3/library/heapq.html